Custom_add_to_cart_link.php

/**
 * Changing add to cart link with custom Text
 * @author Saiful Islam
 * 
 * @global type $product getting Global Product variable for getting permalink
 * @return String Add to cart button link change
 */
function sfl_woocommerce_custom_add_to_cart_link_for_shop(){
    global $product;
    $data = $product->get_data();
    $product_permalink = get_the_permalink($data['id']);
    return '<a class="button your_button_class" href="'. $product_permalink .'">Details Text</a>';
    
}
add_filter('woocommerce_loop_add_to_cart_link','sfl_woocommerce_custom_add_to_cart_link_for_shop');